Cellulosic structures and method of preparing same



Patented 0., 19, 1937" I v UNITED "sTA'rEs 2,096,146 a i CELLULOSIC STRUCTURES AND METHOD, j .-orrm:ranmcsm I Fenton H. Swez ey, Waynesboro, Va, assignon'by mesne assignments, to E. I. du Pont do He mourn & Company, Wilmington, DeL, a corporation of Delaware z No Drawing. Application June 11. 1535,

. v Serial No. zaoss 6 Claims." (cl. 1854) This invention relates to non-flbrouscellulosic pellicles, threads, bands,- tubes and the like, and

more particularly relates to colored pellicles. threads, bands, tubes and the like produced from cellulose esters, and the method of preparing such colored structures. 1

Great difilcult'y'has been'xperienced in the coloring of cellulose esters for example, 'cellu lose acetate,,so as to obtain a colored pellicle, 1o thread or fabric in which the color or dye is fast to light and to an alkaline scouring boil-off operation. Since theproduction of, cellulose acetate yarn on a commercial scale, it has been found necessary to develop new dyes and/or methods of dyeing whereby to. produce a desirable. product,

inasmuch as previouslyjknown dyes werevfound to be inefficient and in a great many cases inoperative for the dyeing of cellulose acetate.

These newly developed dyes are. in some cases 20 quite expensive or involve expensive methodsof applying them to the yarn or fabric.- Furthermore, the colors available'in these new dyes are somewhat limited in comparison to the available I, colors in previously known dyestuffs, the use of whichwas found to be inexpedient fordyeing cellulose acetate materials.

By using previously known dyestuffs through modified methods of application fair'results were obtained in some cases but'such modified procedures were often expensive and time-consuming,and often depended upon the use of an ex pensive auxiliary dyeing rnedium. Furthermore,

both. the newly developed dyes and modified methods of applying previously known (15785 Kenerally involve a poor exhaustion of the dye' from thedyebaths. v

Acid dyes and particularly water-soluble acid dyes are generally known to possess very little or no amnity for cellulosev esters, such as cellulose acetate, and in fact advantage. has been taken of the relatively small afflnity of acid-dyes to cellulose acetate to impart fugitive tints to acetate thread. In case of a fewacid dyes a more or less I permanent coloration results on the thread,;ifa a solvent for cellulose derivative ispresent in the I thread, but even these dyes cannot be applied in a manner to give a uniformly dyed thread, and generally they will not withstandbofling with water containing a small-amount of-sodiumcar- The surprising discovery has now been made that cellulose esters, such as cellulose acetate, can be successfully dyed with water-soluble acid dyes by incorporating a solution orsuspension of the said acid dyes in a cellulose ester solution prior fast to alkaline scouring boil-oil solutions.

to the formation of pellicles (ii-filaments therefrom. 'The colored structures formed from such colored solutions of cellulose acetate or'th'e like are found to be fast to light and comparatively Although it is generally known to incorporate 6 dyes in solutions of cellulose acetate, such previously known processes are limited to the use of insoluble colored pigments, to compounds which will form insoluble dyes upon'subsequent treat- 10 ment, and to water-insoluble dyes.

It is therefore an object of this invention to produce colored films, filaments and fabrics of I cellulose esters, such ascellulose acetate, dyed with water-soluble acid dyes which are substantially fast to light and securing boil-oil operations. It is a further object of this invention to produce f films, filaments and fabrics of cellulose esters, such as cellulose acetate, having watersoluble acid dyes incorporated throughout the body thereof. I I It is another object of this inventlonto provide a method of producing water-soluble acid dyestufi' colored films, fabrics andfilaments of cellulose esters, such as cellulose acetate, which colors are fast to light and securing boil-ofi operations. Other objects ofthe invention will appear hereinafter. .The objectsof the invention can be accomplished in general by dissolving or suspending water-soluble acid dyestuffs in hot or cold water or other suitable liquid medium, mixing a quantity of the dye solution or suspension with a quantity of a solution of a cellulose ester to obtain auniform dispersion and spinning or castingthecolu ored cellulose ester into the form of a filament or'film.

By the term acid dyes as used throughoutthe specification and claims is meant not only those members of the triphenylmethane group generally classified as acid dyes, but alsolthose dyes which contain one or more sulfonic acid groups in the form of sodium, potassium, calcium or ammonium salts or which contain phenol groups I associated with'nitro groups. W 5 The present invention'has particular utility and is described with specific reference to the dye ing of cellulose acetate structures. It is nevertheless to be understoodthat it lsnot to be limited thereto but that the invention is generally-ap-f 5 plicable to'the production of colored flhnsia d l filaments fof celluloseesters, 'suchas cellulose formate, cellulose propionate, cellulose butyrate,"

cellulose phthalate, and mixedYcellulose' esters,

such'as cellulose acetate formatc, celli'ilose acetate-propionate, cellulose propionate-butyrate and. the like.

A water-soluble acid dye, such as Pontacyl Carmine 2-0, (Rowe Color Index No. 31), Pontacyl Brilliant Blue A, (Rowe Color Index No. 714) Pontacyl Black BX, (Rowe Colorlndex No. 246) PontacylI Fast AB, (Rowe Color lndexgNo. 176), Pontacyl Light Yellow 3-6 (Rowe Color Index No. 636), or Pontacyl Fast Black BBO,

(Rowe Color Index No. 307), is dissolved in hot or cold water or other appropriate liquid medium to form a solution, suspension or paste 0! suitable consistency and dependingupon the shadedee sired. The resulting dye solution or paste is then thoroughly mixed with a suitable quantityoi aisolution of cellulose acetate, for example, a solution of cellulose acetate in acetone. The solucarried out inany suitable manner by reason oif tion or cellulose acetate may, itdesired, containz natural or synthetic resins, plasticizers, softeners or similar compounds. such as may be added to produce cellulose acetate structures having sp eelal characteristics. mixing of the solution 01' cellulose acetate and the dye solution may be the fact that the solutions can be easily quickly brought to a homogeneous The resultant homogeneously colored mixture is then spun or cast into filaments or films by any of the conventional .dry or wet methods. j j The acid dye may, if desired, be added, intlts solid form to a solutionof a cellulose ester al ready containing a solvent in suitable proportions,

and by suitable homogenization meth Among the liquid mediums whichmaybe substituted for water to form solutions or 'suspen slons with the acid dyes may be mentioned acetone,'mono-, di-, or polyhydric alcohols, esters, aniline, nitrobenzene, ethylene, chloride, mono-. di-, or 'trl-alblolamines, or mixtures of two 'or more thereof. l

The depth of color imparted to thematerials may be exactly and easily regulated by varying the amount oi dye added to the cellulose acetate solution. Anycolor or shade knownin the prescut an maythusbe obtained in accordance with this invention. Furthermore, acid dyestutisimay be blended with vat dyes, basic dyes, and other classesor dyes, y proper care of selection, such as is well known'in the art, and mixed with a solvent and a cellulose acetate solution to obtain very satisfactory results.

The quantity oi water or other solventor liquid medium in which the water-soluble acid dyestui! is dissolved or. suspended should not exceed 20% bywei'ght ofthedyed cellulose ester or suspension when a thread or film of good physical characteristics is desired, and preferably the quantity oi'Ysaid .water [or othertliquid is kept below 10%, oreven mby weight or the dyed cellulose ester solution. l It it is desired to obtain a delustered or opaqued colored film or fllame'ntfinorzanic Pigments, such as titanium oxide, barium oxide, zinc oxide or antimony white, or organic delusterants, can .be incorporated in the in the usual manner.

Threads dyed in accordance with this "inyen- ,tion can in addltion'be temporarily tinted with,

fugitive dyes for pin-poses or ld ntmeetlonfen which may later be removed, if desired, without aflecting the permanent colors imparted thereto.

' and resultant product of the present iny'ention, 15

In order to more clearly set forth the'process the following illustrative exanlples are given, it

Blue A '(Color Index No. 714) is added to {25% 1 thread or fllm'will beoolot-ed alight yellow wmth dyed cellulose ester solution alkaline b 11 ws being understood theinvention is notto bo limited theretojin any way. j

trample It 1 A quantity oi Index No. 8l)'is dissoivedln; water te lll-v perature and theresulting :aolutionis diluted to a concentration or": liter. suitable ,quantitmior example, ,8 cc. 0! the dye solution is added to 1000 grams 0! a 26% solution of cellul0 lose acetate in rise-substances are agitatedlto-torm a uniformly inanydesirablemanner. Aiilmorthre'ad which:

is-casttorspun is dyed a bin! color-which is oi-e'xcellent iastness to II to an-alkaline scouring boil-oi! operation. I

a rum ur: a "A 1% aqueous solution :or

solution 0! in m proportion of aboutafl to. dye solutionto' grams acetate solutions; cellulose acetate solution contains suillcient flnely divided dclllle terant, such as a dull 1 thread. The components aleag'itated to form a uniform i'stspun or out into a thread or mm whichls alight blue to to alkaline scouring operation Example!!! and which; is or excellent Mom to light and 7 A tense a medei it-fros s as f a n' a e' n rronortion rsbout (Color IndexNo. 24.6 is added with; stirring to a 22% solution-or cellu- 5 l s'p t0 The components are geneous which is or 'cast thread or film. The threadforillm a bluish black which is fast tolight and comparatively rest to an alkalinescom'ing boil d]! oper ationg i- 'Adye solutionof Pqn acyl' A8 (Color. Index No. 176) is preparedby dissolving same in water too. concentration'oi about {grams per-liter. An' aliquot portionjoi the .dye solution I is added to a,23% solutionfof'cellulolo in the proportion of about 8 cc. of the dye to 1000 grams of acetate solutiomand theoom- 'ponehts suitably homos nioed. spun or cast'trom ,the .mixturo'ia colored a "reddish 'pink;which. jl8, isttqtollght so paratively fast toan operation. it t t. t. ummy.

. A dyedicellulose Pontacyl lightgyellowra efl'wwolor-index 'lto. ;636), is prepared in withymmiilo I f and'spunorcast 'into a" -threador isfast to light and fast toanam as 1 i mafi uf lfl PM? seated v1 j. i

' A dyedcellulose acetate solution, Pont'acyi Fast sleernsoiicoloe Index so; m to lerr m d 1n aw dan ewithglxamnle III dyed cellulose acetatesolution is spun orcast into athread' or him "a dart blue color which is'i'ast to'liglit'andcomparativelyhit I Pontacyl Ca-rm'ine a-otooior 5 Dyedthreadsandflhnsproducedinaccordance with this invention are in most cases exceedinglyiasttolightandtotheactionoiboilingwater I containing a smallquantity of soap and sodium 5 carbonate. Thisis a remarkably surprising result in view of the fact that those acid dyes which are water-soluble generally possess little or no aflinity i'or cellulose acetate when applied to unished materials produced therefrom;

o In general, dyes for cellulose acetate are expen-j sive and do not exhaust well trom dye baths;

consequently, the dyeing oi materialsconstructed o! cellulose acetate, as practiced heretofore, is a comparatively expensive procedure.

5 The present invention makespossible the use oi acid dyes, some of which are comparatively inexpensive, moreover. none of thedyestui! is lost in producing thecolored materials. I A

A further advantage of the present invention n lies in the fact that the depth of color imparted I to the material can be predetermined with great" exactness by regulating the quantity of dye added to the cellulose acetate solution; Furthermore,

any desired shade and color known is easily oh- 1 .tainable. e I

In contrast to the use of relatively complicated special colloidal mills and homogenization methods required in producing colored yarn by addition of insoluble colored pigments to the spinning or casting solutions, the present invention requires no special'mixing apparatus and only a short time to mix the dissolved dye uniformly into the acetate solution. I

Since it, is obvious that various changes and is modifications may be made in the above descripe a dye bath and. mixing said solution and a delus- I terlng agent with a solution of a cellulose ester,

and forming said threads and pellicles from said 50 dyed, delustered ester sohition;

thread irom'said dyed acetate solution.

I m'ronn..- we

amiss I 2. The process of producing a ertiiicial thread composed essentialLv of cellulose acetate, which comprises the steps-o! dissolving in a solvent therefor a water-soluble acid d: z

which has substantially no afllnity ior said thread *5, i u

I when applied externally thereto from a dy'e bathand mixing said solution and a delustering agent with water, adding said mixture to a solution of cellulose acetate in acetone,-and spinningsaid thread from the dyed, delustered acetate solu-io s. The process er producing arti ilcial'tbreadsand-pellicles composed essentially of an organic j cellulose ester which comprises the steps of at I v least partially dissolving in a solvent therei'or a is 1 water soluble acid dye which substantially no aiiinity for said threads and pellicles when applied externally thereto from a dyebath, mixing said dye solution with a solution'oi a cellulo'se ester, and rel-mm; said threads and pellicles so i from the dyed ester solution;

4. The process oi producing artificial v and pellicles composed essentially of cellulose I acetatewhich comprises the steps of at least partially dissolving, in a solvent therefor a water sol.- 26 v uble acid dye which has substantially noamnity for said threads andpellicles when applied ex- 'ternally'thereto from a dye bath. mixing said dye solution with a'solution oi cellulose acetate 7 and forming said threads and pellicles from the dyed acetate solution. I a

5, The processvoi' producing/dyed artificial threads and pellicles-composed essentially of an, i organiccellulose ester which comprises the steps oi dissolving in water a water soluble acid dye which has substantially no aiilnity for said thread when applied externally thereto from a dye bath, I

mixing said aqueousdyesolutlon with a solution of a cellulose ester, and spinning said thread from saiddyedester solution. I ,7 H '6. The-process of producing dyed artificial I threads and pellicles composed'essentlally oi cellulose acetate which comprises the steps 0! dissolving in water a water soluble acid dye which has substantially no ailinity'for said thread when i applied externally thereto from a dye bath. mixing, said aqueous dye solutionwith a solution of cellulose acetate in acetone and spinning said 

